Dolphins form decades of social bonds and cooperate between and between cliques, to help each other find mates and fight competitors, new research has found previously unconfirmed behavior among animals.
“These dolphins have long-term stable alliances and have intergroup alliances. Alliance alliance alliances, really, “said Dr. Richard Connor, a behavioral ecologist at the University of Massachusetts at Dartmouth and one of the lead authors of the paper.” But prior to our study, it was thought that cooperative alliances between the groups were unique to humans. “
The findings, published Monday in the journal Proceedings of the National Academy of Sciences, appear to support the “social brain” hypothesis: that mammalian brains have evolved to be larger in size for animals that track their interactions and networks. social. Humans and dolphins are the two animals with the largest brains relative to their body size. “It’s not a coincidence,” Connor said.
Connor’s team of researchers collected data between 2001 and 2006 by conducting intensive boat surveys in Shark Bay, Western Australia. Researchers tracked dolphins by observing and listening to them, using their unique identifying whistles to tell them apart.
They observed 202 Indo-Pacific bottlenose dolphins (Tursiops aduncus), even during the high mating season between September and November.
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Back in the lab, they examined the data by focusing on 121 of these adult male dolphins to observe the patterns on their social networks. And for the next decade they continued to analyze animal alliances.
The social structures of dolphins are fluid and complex. The researchers found alliances between two or three male dolphins as best friends. Then the groups expanded to 14 members. Together, they have helped each other find females to herd and mate with, and help steal females from other dolphins and defend against any attempted “theft” of rivals.
“What happens as a male, you could be in a threesome, grazing a female. And if someone comes to get that female, the other males on your team and your second order alliance come in and help you, ”said Dr Stephanie King, Professor of Animal Behavior at the University of Bristol and one of the authors. “These males have a very, very clear idea of who is on their team.”
These teams can last for decades and form when dolphins are still young, although they don’t tend to reap the rewards of parenthood until mid-teens, King said. “It’s a significant investment that starts when they are very young and these relationships can last a lifetime.”
Sometimes, especially when groups of dolphins feel there is a risk to themselves, even two second-order alliances come together to form a larger team. Consequently, among the dolphins observed by the scientists, each male was directly related to between 22 and 50 other dolphins.
The researchers’ observations show that in these groups, the tighter the clique – and the stronger the bonds between the dolphins – the more successful they are in attracting females.
It’s their cooperative relationships, rather than the size of the alliance, that give males greater reproductive success, King said.
It is already widely known that dolphins are highly social and cooperative, as well as being extraordinarily good at adapting and teaching behaviors specific to their environment, said Stephanie Venn-Watson, former director of translational medicine and research at the National Marine Mammal. Foundation in San Diego, California, which was not involved in the study.
“The possibility is not ruled out that other cetaceans may develop similar alliances,” said Venn-Watson. “These complex behaviors are likely to be limited to large-brain mammals.”
According to the researchers behind the paper, this is the only non-human example of this type of multi-level strategic alliance to have been observed. But these findings also highlight the cognitive needs these animals face, suggesting the dolphin’s large brains help them keep track of different relationships, Connor said.
“I would say that dolphins and humans have merged into the evolution of alliances between groups, an incredibly complex social system,” said Connor. “And it’s amazing why we’re so different from dolphins.”